Bridge parapet collapse between Laurencekirk & Stonehaven (15/01)

[swt_passenger]

Given that there was no accident or near miss there isn't really anything for them to investigate.

There doesn’t really have to be a near miss. I mentioned the actual wording in the Nine Elms discussion, linked in post #108 there. It’s fairly wide ranging:
“The failure of a structure on railway property, including a tunnel, bridge, viaduct, culvert, railway cutting, embankment, station, signal or fixed electrical equipment which under slightly different circumstances may have led to a serious accident or which otherwise reduces the level of railway safety.”

 

[Nicholas Lewis]

Given that there was no accident or near miss there isn't really anything for them to investigate.

I get where your coming from but RAIB have investigated or at least put out a safety digest on plenty of incidents/near misses where no harm has occurred. The point being a potential to cause harm has plenty to learn from and is better than waiting for an event to occur to ten determine root cause.

 

[edwin_m]

I'd expect an investigation here. There's potential here for a train to go off the bridge if for example heavy rain had eroded out further underneath the track or a couple of trains had passed through at night (so the damage wouldn't have been visible) allowing the track to move outwards. They investigated the bridge at Barrow-on-Soar where part of the sidewall came down on the track, and this could have been just as serious if things had gone differently.

 

[GRALISTAIR]

I'd expect an investigation here. There's potential here for a train to go off the bridge if for example heavy rail had eroded out further underneath the track or a couple of trains had passed through at night (so the damage wouldn't have been visible) allowing the track to move outwards. They investigated the bridge at Barrow-on-Soar where part of the sidewall came down on the track, and this could have been just as serious if things had gone differently.

EXACTLY

Given that there was no accident or near miss there isn't really anything for them to investigate.

I disagree

 

[swt_passenger]

I'd expect an investigation here. There's potential here for a train to go off the bridge if for example heavy rail had eroded out further underneath the track or a couple of trains had passed through at night (so the damage wouldn't have been visible) allowing the track to move outwards. They investigated the bridge at Barrow-on-Soar where part of the sidewall came down on the track, and this could have been just as serious if things had gone differently.

The Feltham River Crane bridge collapse was another one thoroughly investigated, with the incident not affecting trains at the time, ie it was spotted just in time.

 

[snowball]

As RAIB seem disinterested in this and Nine Elms doubt we will every really know but maybe and FOI would liberate an answer.

They're supposed to be disinterested, i.e. unbiased. I think you meant to accuse them of being uninterested.

 

[InOban]

Surely the RAIB should be interested in preventing any future events cause by a failure of safety - critical infrastructure . And the parapet must be safety-critical, otherwise the line would not have to be closed for emergency repairs. It's repair would have been put into the long-term program of works, like the renovation of any other bridge.

 

[edwin_m]

The parapet would have to be replaced in some form even if there was no risk to the trains, because there would be a risk of track workers and anyone climbing down from a train falling into the river. But if that was the only reason to replace it then a non-structural barrier such as a rail made from scaffolding would be sufficient.

 

[P Binnersley]

The parapet failure will have been investigated internally by Network Rail and I would expect the results to have been passed onto RAIB.

The Carmont investigation includes:

• the management of earthworks and drainage in this area, including recent inspections and risk assessments
• the general management of earthworks and drainage and associated procedures designed to manage the risk of extreme weather events

Opening a new investigation will probably end up duplicating the above which could include this incident as part of its scope.

 

[Nicholas Lewis]

The parapet failure will have been investigated internally by Network Rail and I would expect the results to have been passed onto RAIB.

The Carmont investigation includes:

• the management of earthworks and drainage in this area, including recent inspections and risk assessments
• the general management of earthworks and drainage and associated procedures designed to manage the risk of extreme weather events

Opening a new investigation will probably end up duplicating the above which could include this incident as part of its scope.

The parapet forms part of a structure and won't be covered by this remit on earthworks. Despite the unusual nature of this failure and Nine Elms RAIB are treating it like a broken rail or a wrong side signalling failure and leaving it to NR. ORR maybe come interested when they say to the regulatory part of ORR "oh we've discovered our parapet walls are weaker than we thought so we need more funding for asset renewals in this area come CP7"

 

[AndrewE]

As lateral pressure from ballast and trains is almost certainly behind these failures, let's hope that the reconstruction thinks ahead and doesn't just replace like with like. It's a tragedy that repairs keep being made which perpetuate problems simply because it's forbidden to improve anything on the maintainance budget.
Forget geotextiles (mentioned above, but with no structural strength.) Go with concrete retaining wall sections, they are not new technology, or even new to the railway: my picture shows a new railway overbridge sidewall. Why not put these down under the track on an underbridge instead and use the track's weight to anchor the side-walls?
(I think I know the answer: not invented here!)
A

 

[PG]

Go with concrete retaining wall sections, they are not new technology, or even new to the railway: my picture shows a new railway overbridge sidewall. Why not put these down under the track on an underbridge instead and use the track's weight to anchor the side-walls?

Forgive my naivety but wouldn't that cause the side-walls to flex ever so slightly each time a train passed?

 

[Nicholas Lewis]

Forgive my naivety but wouldn't that cause the side-walls to flex ever so slightly each time a train passed?

Basically when victorians built viaducts track was laid level on clinker. Over the years its been replaced with ballast and modern track mechanisation largely results in level of track increasing for decades before a renewal comes along. Then we've had various speed improvements schemes over the years achieved through canting of track and we now find ourselves with a wall that was there to prevent people falling from height now needing to provide a level of structural integrity it wasn't necessarily designed to do. To be fair there have been many schemes to lower walls and provide steel walkways often as part of resignalling schemes but would be interesting to know what the designers considered for track canting schemes. I suspect clearances only and this may be a hidden wider problem that this incident has revealed. Shame RAIB are not taking an interest as all these questions would be answered.

 

[AndrewE]

Forgive my naivety but wouldn't that cause the side-walls to flex ever so slightly each time a train passed?

I was picturing them sat on the solid top of the filled-in arches (so a part of the structure,) well below all the drainage and layers of ballast.

 

[edwin_m]

It would make a lot of sense for RAIB to combine it with Carmont.

As lateral pressure from ballast and trains is almost certainly behind these failures, let's hope that the reconstruction thinks ahead and doesn't just replace like with like. It's a tragedy that repairs keep being made which perpetuate problems simply because it's forbidden to improve anything on the maintainance budget.
Forget geotextiles (mentioned above, but with no structural strength.) Go with concrete retaining wall sections, they are not new technology, or even new to the railway: my picture shows a new railway overbridge sidewall. Why not put these down under the track on an underbridge instead and use the track's weight to anchor the side-walls?
(I think I know the answer: not invented here!)
A

Something pretty similar was used during the last big Dawlish washout. I believe these are also L-shapes with the horizontal buried under the track, but I can't immediately find a photo to confirm.
https://i.dailymail.co.uk/i/pix/2014/04/04/article-2596736-1CCDE7A100000578-102_962x721.jpg (you don't have to read any of the Daily Mail if you follow this link)

 

[Durradan]

The line is due to reopen Monday as planned:

Stonehaven-Montrose railway set to reopen for customers​

Region & Route: Scotland’s Railway: Scotland
The railway between Stonehaven and Montrose will reopen for passenger and freight customers on Monday, February 22, following the successful completion of repair works on a damaged bridge between the towns.

The rail bridge – which dates from the 1840s and is located three miles north of Carmont – has been closed since January 15 after masonry fell from the sidewall (parapet) on the southbound side of the structure.

Network Rail engineers, and specialist contractors, have been working around-the-clock since to carry out full structural assessments of the bridge, complete parapet repairs and strengthen the structure.

These works have included:

• Installing additional concrete supports on the bridge deck to help retain and support the track and ballast.
• Reconstructing the failed parapet wall.
• Installing ties through the bridge to strengthen the overall structure.
• Relaying new track and supporting ballast on the
  southbound side on the bridge.

I was worried the weather last week might have slowed the repairs, but evidently not.

Why are they waiting until Monday to reopen if the repairs are completed? Easier logistically to start from a fresh week?

 

[PG]

Why are they waiting until Monday to reopen if the repairs are completed? Easier logistically to start from a fresh week?

Final inspection of the line to be carried out on Sunday apparently, listed further on in the link you provided.

Extensive trackside and aerial surveys of the railway between Stonehaven and Montrose have also been carried out in advance of reopening, with final line checks to be completed on Sunday morning.

 

[Durradan]

Final inspection of the line to be carried out on Sunday apparently, listed further on in the link you provided.

Yes, I saw that. That's why I'm wondering why they're waiting rather than say opting to do the final checks tomorrow and reopen before the weekend.

 

[PG]

Yes, I saw that. That's why I'm wondering why they're waiting rather than say opting to do the final checks tomorrow and reopen before the weekend.

Can't answer that, maybe someone else knows?

 

[mcmad]

Think the line was blocked over the weekend for planned engineering works so presumably little point opening Friday to shut straight back down again?

 

[Durradan]

Think the line was blocked over the weekend for planned engineering works so presumably little point opening Friday to shut straight back down again?

I didn't realise the works were still going on. That makes sense.

 

[mcmad]

The line is blocked at weekends at this time of year for normal renewals of track and suchlike, no idea if the works at the viaduct are complete but article you quoted above states they are so(at least) 2 different sets of work.

 

[InOban]

Given that traffic is so low, I don't understand why NR persist in the inefficient practice of closing a route for several Sundays instead of one longer possession. I'm sure they could deliver all the work in a 2-3 day block. But that's OT.

 

[scotraildriver]

Given that traffic is so low, I don't understand why NR persist in the inefficient practice of closing a route for several Sundays instead of one longer possession. I'm sure they could deliver all the work in a 2-3 day block. But that's OT.

Because most works are planned, contracts let, machinery sourced etc 1-3 years before the work starts. This would all be planned long before Covid.

 

[pdeaves]

Because most works are planned, contracts let, machinery sourced etc 1-3 years before the work starts. This would all be planned long before Covid.

There are a few places where it has been possible to bring forward work to fit the quieter network, but that is the exception rather than the rule. Almost an 'accidental outcome' that fits in with all the many diaries.

 

[Zanahoria]

Some photos of the new parapet from the Railscot website:

Carron Water Bridge [East Croft of Carmont] - RAILSCOT

RailScot, a history of Railways with an emphasis on Scottish Railways. Photographs, maps, news, queries and more.

www.railscot.co.uk

Carron Water Bridge [East Croft of Carmont] - RAILSCOT

RailScot, a history of Railways with an emphasis on Scottish Railways. Photographs, maps, news, queries and more.

www.railscot.co.uk

 

[swt_passenger]

Some photos of the new parapet from the Railscot website:

There’s quite a few more interesting photos on that site, but the two you’ve embedded are the same pair as in the earlier Network Rail press release, linked in post #76.

 

[AndrewE]

I am pleased to see that the construction method has been brought up to date! It was probably quicker than rebuilding the brick wall would have been too.
I guess procuring panels with a brick skin would have delayed the job, but would have looked better. I wonder whether there is enough "commonality" for a standard product to be commissioned and held for use as needed? There were 2 of this type of failure very close together (in time.) How many other potential failures will emerge from a network-wide survey?

 

[Zanahoria]

There’s quite a few more interesting photos on that site, but the two you’ve embedded are the same pair as in the earlier Network Rail press release, linked in post #76.

Drat! My apologies - I really thought I had a scoop there!

 

[swt_passenger]

Drat! My apologies - I really thought I had a scoop there!

I hoped it might encourage people to follow the link anyway though. Must have been a difficult job in recent weather conditions.